February 1, 1998
Is it a Carcinoma or a Lymphoma? |
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Diagnosis
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| Discussion | ||
| Because of the
differences in effective chemotherapy regimens, it is
important to make the distinction between a poorly
differentiated carcinoma and a lymphoma. In this case,
the light microscopic features could be those of either a
carcinoma or a lymphoma. Immunohistochemical staining of
the neoplastic cells suggested that the malignant tumor
in the lymph nodes was probably a carcinoma and not a
malignant lymphoma. Electron microscopy of tissue from
the paraffin block demonstrated primitive, intercellular
junctions and thus this study confirmed the diagnosis of
and undifferentiated carcinoma. This case demonstrates the utility of ultrastructural analysis in the solution of a common diagnostic problem, the differentiation of a carcinoma from a lymphoma. The presence of junctions in lymphomas and lymphoreticular tissues is controversial. However, in a majority of reports in the literature, there are no intercellular junctions between hematopoeitic cells 1. Thus if primitive junctions are found in an undifferentiated tumor, this morphologic feature excludes a diagnosis of lymphoma. Primitive junctions are not unique to carcinomas. They can be found in sarcomas as well as a number of neoplasms that are neither sarcomas nor carcinomas 2. The location of the tumor and negative immunohistochemical staining with the markers for melanoma, malignant peripheral nerve sheath tumor and germ cell tumor are additional support for rendering a diagnosis of an undifferentiated carcinoma. |
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| References: | ||
| 1. | Ghadially FN. Is it a Carcinoma or a Sarcoma. In: Diagnostic Electron Microscopy of Tumours 2nd ed. Butterworths, Boston; 1985. pp 65-86. | |
| 2. | Erlandson RA. Cell Junctions. In: Diagnostic Transmission Microscopy of Tumors. Raven Press, New York; 1994. pp 207-219. | |
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